diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index be2a68a09d19..6073e342a1ed 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -611,6 +611,10 @@ static void check_xstate_against_struct(int nr) * This essentially double-checks what the cpu told us about * how large the XSAVE buffer needs to be. We are recalculating * it to be safe. + * + * Dynamic XSAVE features allocate their own buffers and are not + * covered by these checks. Only the size of the buffer for task->fpu + * is checked here. */ static void do_extra_xstate_size_checks(void) { @@ -673,6 +677,33 @@ static unsigned int __init get_xsaves_size(void) return ebx; } +/* + * Get the total size of the enabled xstates without the dynamic supervisor + * features. + */ +static unsigned int __init get_xsaves_size_no_dynamic(void) +{ + u64 mask = xfeatures_mask_dynamic(); + unsigned int size; + + if (!mask) + return get_xsaves_size(); + + /* Disable dynamic features. */ + wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()); + + /* + * Ask the hardware what size is required of the buffer. + * This is the size required for the task->fpu buffer. + */ + size = get_xsaves_size(); + + /* Re-enable dynamic features so XSAVES will work on them again. */ + wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask); + + return size; +} + static unsigned int __init get_xsave_size(void) { unsigned int eax, ebx, ecx, edx; @@ -710,7 +741,7 @@ static int __init init_xstate_size(void) xsave_size = get_xsave_size(); if (boot_cpu_has(X86_FEATURE_XSAVES)) - possible_xstate_size = get_xsaves_size(); + possible_xstate_size = get_xsaves_size_no_dynamic(); else possible_xstate_size = xsave_size; |